RUT Registration and Employer Change in Denmark 2026

RUT registration is one of the most practical yet frequently misunderstood obligations facing Polish workers and agencies operating in Denmark. When a Polish staffing agency unexpectedly loses its contract with a Danish construction company or other employer, the RUT record does not update itself. The clock starts ticking immediately, and both the outgoing agency and the workers themselves face real legal exposure if the situation is left unresolved. This guide walks through every step required to handle a change of employer in the RUT system correctly, so that no one ends up on the wrong side of Arbejdstilsynet.

What Is the RUT Register and Why Does It Matter?

The Register of Foreign Service Providers, known in Denmark as RUT (Registret for Udenlandske Tjenesteydere), is maintained by Arbejdstilsynet, the Danish Working Environment Authority. Under Danish law, any foreign company that posts workers to Denmark is required to register before work begins. The obligation applies to Polish agencies sending construction crews, cleaning teams, and other service workers across the border. The registration must reflect the actual employer of record at all times. When a Polish agency loses its Danish contract and a new arrangement takes over, the outdated entry in RUT becomes a compliance problem for everyone involved.

Danish law on posted workers, implementing the EU Posted Workers Directive, gives Arbejdstilsynet the authority to inspect worksites and verify that RUT entries match reality. Fines for non-compliance can reach tens of thousands of DKK, and repeated or deliberate violations attract heavier penalties. For workers already on site, an incorrect RUT entry can also complicate questions around social security coverage and tax residency. If you are wondering how Danish income tax interacts with your situation as a posted worker, the article Who Pays Income Tax When a Pole Works Seasonally in Denmark 2026 covers that in detail.

Step 1: Establish What Has Actually Changed

Before touching the RUT portal, the agency and the Danish client need to agree on exactly what the new employment arrangement looks like. Has the Danish company taken the workers on directly? Has a second Polish agency assumed the contract? Is the original agency winding down its Danish operations entirely, or simply transferring one project? The answer determines which party must file the new RUT notification and which party must close the old one. Getting this wrong at the start causes cascading errors in the paperwork that follows.

Check the Original Contract and the Posted Workers Documentation

The original service contract between the Polish agency and the Danish client will specify the legal employer of the posted workers. Polish agencies operating under the Kodeks Pracy must also verify that any transfer of workers complies with Polish employment law, including notice obligations. The Polish State Labour Inspectorate, PIP (Państwowa Inspekcja Pracy), can be consulted if there is any doubt about whether the agency's obligations to workers have been properly discharged during the transition.

Step 2: Gather the Required Documents

The entity that will become the new registered service provider in RUT needs to have the following ready before logging into the portal: its Danish CVR number or, if it is a foreign company without a Danish registration, its home-country company registration number; the names and Danish CPR numbers or passport details of all workers being posted; the address and nature of the worksite; and the expected start and end dates of the posting. If the workers are to be covered by a Danish collective agreement, the relevant agreement details should also be on hand. For construction sites, this often means referencing the rates and conditions set by 3F, the Danish union for unskilled and semi-skilled workers. A broader look at those rates is available in the guide Minimum Wage on Danish Construction Sites 2026: 3F Rates, Night and Holiday Supplements Step by Step.

Step 3: Use the Official RUT Portal

Notifications are submitted through the official Arbejdstilsynet portal at at.dk. The portal is available in Danish and English. The outgoing agency must log in and either close its existing notification or update it to reflect that the posting has ended. The incoming employer, whether a new Polish agency or the Danish company itself, then creates a fresh notification covering the workers who will continue on site. Both actions should happen on the same business day to avoid a gap in coverage. Arbejdstilsynet's own guidance on the RUT registration process is published directly on the authority's website and is updated regularly.

Step 4: Notify the Relevant Social Security Institutions

A change of employer in Denmark also has consequences for social security coverage. Polish workers posted to Denmark under an A1 certificate issued by ZUS (Zakład Ubezpieczeń Społecznych) remain covered by Polish social insurance for the duration of the posting, but the A1 certificate is tied to a specific employer. If the employing entity changes, the original A1 certificate may no longer be valid and a new application must be submitted to ZUS. Failing to do this creates a situation where the worker appears uninsured in both countries, which is a serious problem in the event of a workplace accident. The ZUS portal at zus.pl provides the forms and guidance needed for A1 applications and amendments.

Step 5: Confirm the Update and Keep Records

Once both the closure of the old RUT entry and the creation of the new one have been submitted, the responsible person at each company should download and store the confirmation documents. Arbejdstilsynet issues a reference number for each notification. That reference number should be kept on file and, ideally, posted visibly at the worksite alongside other mandatory documentation. If an inspector arrives during the transition period, having the confirmation at hand demonstrates good faith and substantially reduces the risk of a fine.

Common Mistakes to Avoid

One of the most frequent errors is assuming that the Danish client will handle the RUT update on behalf of the outgoing Polish agency. Under Danish law, the obligation rests with the foreign service provider, not the Danish recipient of the service. Another common mistake is updating RUT but forgetting to inform ZUS about the change of employer, leaving workers with invalid A1 certificates. A third pitfall is treating the transition as complete once the paperwork is filed, without verifying that the new entry actually appears correctly in the public RUT database. The database is searchable on the Arbejdstilsynet website, and a quick check takes less than two minutes.

For hypothetical context: imagine a Polish agency employing a crew of workers on a Copenhagen renovation project. The Danish general contractor decides mid-project to bring in a different subcontractor. If the original Polish agency simply stops sending workers without filing a closure notice in RUT, and the new subcontractor begins work without its own registration, both parties are technically in violation simultaneously. The Danish client can also face scrutiny in such a scenario, since Danish companies are expected to verify that foreign subcontractors are properly registered.

If the situation involves a formal dismissal of Polish workers as part of the contract loss, the rules around notice periods and workers' rights under Danish employment law deserve careful attention. The article Dismissing a Polish Worker in Denmark 2026: Notice Periods, Arbejdsret and What to Avoid is a useful companion read for managers navigating that side of the transition.

Actionable Advice for Agencies and Workers

The moment a contract loss becomes known, the agency's compliance officer should open the RUT portal and the ZUS A1 file on the same day. Do not wait for the final day of work on site. Contact PIP if there is any uncertainty about Polish-side obligations to the workers. Ensure that the incoming employer, whoever that turns out to be, has completed its own RUT registration before the first day of work under the new arrangement. Keep copies of every submission confirmation, and make sure the workers themselves know the name of the registered employer, because inspectors sometimes ask workers directly. A smooth RUT transition protects the agency's ability to win future Danish contracts, protects workers' social security coverage, and keeps the Danish client out of an uncomfortable compliance conversation with Arbejdstilsynet.